You don't have to have photographic paper in fact it's probably better if you can use the glossy paper for encaustic wax. Why? well the photographic paper is designed for the ink to dry quickly and ebbed itself into the paper when you print on it and the encaustic from what I can remember isn't as porous and so has a slow drying time. Having said that I'm pretty pleased with how these backgrounds have turned out.
I haven't done a tutorial for these as there really is no right or wrong way of making these. I started off by spraying plain water to the paper, then added the spray inks and then sprinkled/splodged/flicked the acrylic ink with an old paint brush. Carry on adding plain water or the spray inks until you are happy with how the paints have merged and then either leave them to dry or use a heat gun.
Pop back again to see how I use these in one of my projects.
Well I'll be back tomorrow - until then happy crafting